1. Field of the Invention
This invention relates to a phase-locked battery charge system, more particularly to a battery charging system emphasizing on simple circuit structure, good charge current, and safe charge conditions.
2. Description of the Related Art
In general, there are different kinds of secondary batteries including lead acid batteries, Nickel-Cadmium batteries, Nickel-Hydrogen batteries, and Lithium-Ion batteries, and thus many charging strategies for the foregoing batteries have been developed, such as a constant trickle current charge, bulk current charge, and constant-voltage/constant-current charge (or also known as constant-voltage restricted-current charge or two-stage charge).
Further, the most popular constant-voltage/constant-current battery charge strategy uses the bulk current to charge a battery from the beginning until a predetermined final voltage is reached. After the predetermined voltage is reached, the battery charger will charge the battery with a constant voltage equal to the value of a predetermined voltage, and the charging current will be decreased automatically. When the charging current is decreased to zero, the battery is regarded as 100% fully charged.
Further, a fuzzy quick charge system having the active state-of-charge detection capability is developed as disclosed in the R.O.C. Invention Patent No. 140649, which can obtain an appropriate value for the charge current to improve the battery charge performance, and neural networks and genetic algorithms are also adopted to harmonize and optimize the variables in the fuzzy control battery charge system in order to obtain a more appropriate charging current.